Synthetic microfluidic blood-brain barrier

Abstract

An apparatus and method for assaying blood-brain barrier properties for drug and drug delivery vehicle screening comprising of a microfluidic apparatus with gaps separating lumen and tissue space enabling formation of tight junctions similar to in vivo conditions using endothelial cells and brain cells.

The invention claimed is: 
     
       1. A method for measuring the ability of a drug or drug delivery vehicle to cross a blood-brain barrier comprising the steps of:
 a) introducing a liquid containing the drug or drug delivery vehicle into a network inlet of an optically transparent plastic microfluidic chip, said microfluidic chip comprising:
 a network of interconnected flow channels in liquid communication with a network inlet and a network outlet, said flow channels having luminal cross-sectional dimensions of between 10 μm and 500 μm and 
 a tissue space in liquid communication with a tissue space inlet and a tissue space outlet, said tissue space having cross-sectional luminal dimensions of between 100 μm and 1 cm wherein: 
 the tissue space is separated from a lumen of at least one flow channel by a liquid permeable wall and is in liquid communication with the at least one flow channel through said liquid permeable wall; 
 the luminal surfaces of the flow channels are coated with endothelial cells; and 
 the luminal surfaces of the tissue space contains brain cells and/or cell growth media; 
 
 b) causing the liquid containing the drug or drug delivery vehicle to move though the network of interconnected flow channels; and 
 c) quantifying the amount of the drug or drug delivery vehicle reaching the tissue space. 
 
     
     
       2. The method of  claim 1 , wherein the surface of the flow channels or the tissue space are coated with a substance selected from the group consisting of a gel, a basement matrix, an extracellular matrix, a tissue matrix, a synthetic matrix, a natural matrix and combinations thereof. 
     
     
       3. The method of  claim 1 , wherein a surface of the tissue space is coated with glial cells, astrocytes, neurons or combinations thereof. 
     
     
       4. The method of  claim 1 , wherein the tissue space contains astrocyte-conditioned media, neural cell-conditioned media, glial cell-conditioned media or combinations thereof. 
     
     
       5. The method of  claim 1 , wherein a surface of the flow channels is coated with endothelial cells (primary or immortalized) originating from brain vasculature. 
     
     
       6. The method of  claim 1 , wherein quantifying the amount of the drug or drug delivery vehicle is performed by a means comprising optical, electrical, chemical or biochemical detection. 
     
     
       7. The method of  claim 1 , wherein formation of tight junctions by cells in the interconnected flow channels and/or tissue space is evaluated using electrical, optical, chemical or biochemical means. 
     
     
       8. The method of  claim 1 , wherein the liquid containing a drug or drug delivery vehicle is moved through the network of interconnected flow channels once, multiple times, or is recirculated through the network of interconnected flow channels using electrokinetic forces, pumps and/or other pumping mechanisms. 
     
     
       9. The method of  claim 1 , wherein a liquid containing a plurality of drugs or drug delivery vehicles is introduced into the network inlet in step a). 
     
     
       10. The method of  claim 1 , and further comprising the method step of measuring a property of the drug or drug delivery vehicle, said property selected from the group consisting of: real-time circulation, stability, half life, rate of aggregation, rate of degradation and combinations thereof. 
     
     
       11. The method of  claim 1 , wherein the drug delivery vehicle or drug is selected from the group consisting of: a cell, a liposome, a lipisome, a lipoprotein, a microencapsulated drug, a particulate drug carrier, a nanoparticle, a microparticle, a nanocrystal, a polymer bead, a virus, a bacterium, a naturally occurring protein, a synthetic protein, a naturally occurring compound, a synthetic compound, and combinations thereof. 
     
     
       12. The method of  claim 11 , wherein quantifying the amount of the drug or drug delivery vehicle reaching the tissue space measurement is performed while fluid is moving within the network or under static fluidic conditions. 
     
     
       13. The method of  claim 1 , wherein the liquid is moved through the network of interconnected flow channels with varying fluidic shear rate values of between 1 sec −1  and 2000 sec −1 , as measured experimentally or predicted by computational simulation. 
     
     
       14. The method of  claim 1 , wherein the liquid is selected from the group consisting of: a cell culture media, a buffer containing serum proteins, whole blood, apheresed blood, a buffer containing leukocytes, a buffer containing erythrocytes, a buffer containing platelets, and combinations thereof. 
     
     
       15. The method of  claim 1 , wherein said network of interconnected flow channels is a synthetic microvascular network or an idealized microvascular network. 
     
     
       16. The method of  claim 1 , wherein said liquid permeable wall comprises impermeable structures separated by a gap distance. 
     
     
       17. The method of  claim 16 , wherein said gap distance is between 0.2 μm and 5 μm. 
     
     
       18. The method of  claim 16 , wherein the gaps are filled with a substance selected from the group consisting of a gel, a basement matrix, an extracellular matrix, a tissue matrix, a synthetic matrix, a natural matrix and combinations thereof. 
     
     
       19. An optically transparent microfluidic chip comprising:
 a) a network of interconnected flow channels in liquid communication with a network inlet and a network outlet, said flow channels having luminal cross-sectional dimensions of between 10 μm and 500 μm and 
 b) a tissue space in liquid communication with a tissue space inlet and a tissue space outlet, said tissue space having cross-sectional luminal dimensions of between 100 μm and 1 cm wherein: 
 the tissue space is separated from a lumen of at least one flow channel by a liquid permeable wall and is in liquid communication with said flow channel through said liquid permeable wall; 
 the luminal surfaces of the flow channels are coated with endothelial cells; and 
 the luminal surfaces of the tissue space contains brain cells and/or cell growth media. 
 
     
     
       20. The microfluidic chip of  claim 19 , wherein the network of interconnected flow channels is a synthetic microvascular network or an idealized microvascular network. 
     
     
       21. The microfluidic chip of  claim 19 , wherein the geometry of the synthetic microvascular is identical to a digitized physiological microvascular network or an average of two or more digitized physiological microvascular networks. 
     
     
       22. The microfluidic chip of  claim 19 , wherein the network of interconnected flow channels comprise bifurcation angles of between 15 and 135°. 
     
     
       23. The microfluidic chip of  claim 19 , wherein the network of interconnected flow channels is an idealized microvascular network comprising flow channels having asymmetric and/or symmetric branches and cross-sections. 
     
     
       24. The microfluidic chip of  claim 19 , wherein the liquid permeable wall comprises structures separated by a gap distance between 0.2 μm and 5 μm. 
     
     
       25. The microfluidic chip of  claim 24 , wherein a surface of the flow channels or the tissue space are coated with or the gaps are filled with a substance selected from the group consisting of a gel, a basement matrix, an extracellular matrix, a tissue matrix, a synthetic matrix, a natural matrix and combinations thereof. 
     
     
       26. The microfluidic chip of  claim 19 , wherein the surface of the flow channels is coated with endothelial cells obtained or derived from the vasculature of a mammalian brain. 
     
     
       27. The microfluidic chip of  claim 19 , wherein pressures are regulated inside the flow channels and the tissue space. 
     
     
       28. The microfluidic chip of  claim 19 , wherein the tissue space contains astrocyte conditioned media, neuronal conditioned media, glial conditioned media or a combination thereof. 
     
     
       29. The microfluidic chip of  claim 19 , wherein a surface of the tissue space is coated with glial cells, astrocytes, neurons, or a combination thereof. 
     
     
       30. An apparatus comprising the microfluidic chip of  claim 19 ;
 means for moving fluid from the network inlet to the network outlet; and 
 means for measuring the integrity of an artificial blood-brain barrier comprising said liquid permeable wall and said endothelial cells selected from the group consisting of optical, electrical, chemical and biochemical detection means. 
 
     
     
       31. An apparatus comprising the microfluidic chip of  claim 19 ;
 pumping means configured to move fluid from the network inlet to the network outlet; and 
 means for detecting a drug or drug delivery vehicle in the tissue space selected from the group consisting of optical electrical, chemical and biochemical detection means.